Short summary describing this game.

Overview

The PS2 version Menu Screen.

In Half-Life, a 1998 first-person shooter and the first release from Valve Software, the player is Dr. Gordon Freeman, a brilliant theoretical physicist and MIT graduate forced to escape the devastated Black Mesa Research Facility after a multi-dimensional experiment generates a resonance-cascade, simultaneously allowing creatures from a dimensional border world, Xen, into our universe and causing catastrophic damage to the facility. Throughout the course of the game the player must battle the Xen invaders, soldiers and an elite Black Ops detachment in an effort to thwart the invasion. Freeman is a silent protagonist, who has never had a single line of dialogue in the course of the franchise, but he remains a deep source of intrigue and discussion due to information learned throughout the course of the series.

Valve released an updated version of the original game, Half-Life: Source, which makes use of the Source Engine to provide new water and physics effects, but did not feature a complete revamp of the game's assets.

Gameplay

Half-Life did little new in terms of control improvements at the time, but there were still many aspects of the genre that it revolutionized at the time of its release. The largest of these advancements was the lack of cut scenes. The story was told through scripted sequences that took place in real-time, in the same environment as the player. This lead to an incredibly immersive experience that players at the time had never seen before. Another important advancement in the genre was the lack of specified stages.

In a sense the whole game was just one big world, not split up into levels. Load times were short and were placed between certain doors or passageways. This little detail allowed the player to feel immersed in the story and the universe, and since the game took place in essentially one location, it made sense that each area was connected to the next.

Plot

The game's protagonist, Gordon Freeman.

At the beginning of the game Gordon Freeman, the protagonist, is on his way to work at the Black Mesa Research Facility, presumably late, which is apparently commonplace for him. That day he is required to participate in a special experiment in the Anomalous Materials Lab in Sector C, where he is to push a crystal into the beam of the Anti-Mass Spectrometer in order to study it. Instantly, this causes a resonance cascade, where a portal erupts between Earth and a world known as Xen.

Freeman reawakens, partially clueless as to what has just happened. Backtracking through the facility, he meets some scientists who brief him on what is happening. According to them contact with the surface is fragmented, although a rescue team is said to be arriving shortly. This later turns out to be the HECU, or the Hazardous Environment Combat Unit, who infiltrate Black Mesa not to rescue but rather to kill everyone involved with the project. Freeman then begins his long journey through the facility, hoping to reach the surface. Along the way, it turns out that the facility has become a war zone between the military and the Xen aliens. Freeman eventually learns about the Lambda Team -- who believe they have what it takes to reverse all this terror.

Along the way Gordon must launch a rocket satellite, with the intent of reversing the resonance cascade, by making his way through the underground, along a rail complex, to the satellite launch location. Gordon then redirects his path back to the Lambda Complex. At this time, the HECU begins to evacuate the facility, and commence air strikes. After that, Gordon no longer encounters military.

Finally, Gordon reaches the Lambda Complex. He has never been to this part of the facility, but learns a lot about the complex. This is where the technology to teleport to Xen was invented, and hopefully where the effects can be reversed. Though, Gordon learns from the few surviving scientists that the rocket satellite he has launched failed, and the only way left in order to reverse the effects is to go to Xen itself and kill the mysterious figurehead alien, Nihilanth. Gordon manages to get to Xen, and after a brief exploration through the planet, Gordon encounters the Nilhilanth. After destroying Nihilanth, Gordon is confronted by the mysterious G-Man.

G-Man can be spotted throughout the game, only briefly, to disappear around a corner and not be seen again. G-Man explains the situation through his fragmented English, stating his employers are interested in him, and that he believes Gordon has limitless potential. He then offers Gordon a job, which he may either reject or accept. If the player accepts, the G-Man is content with his decision, and makes it clear that this will not be the last time he will see him. If the player rejects, he is teleported unarmed to an area representing a place from Xen, surrounded by several Xen Grunts.

Weapons

Half-Life features a host of both traditional and non-traditional weapons. The primary weapons that can be found throughout the game are as follows:

Crowbar

The famous crowbar.

This melee weapon has inexplicably become synonymous with the Half-Life franchise. As a melee weapon, once guns are obtained it should really only be used as a weapon of last resort, and to save ammo when busting open crates and boxes.

Pistol

A basic handgun that can be found in many first-person shooters. The pistol in Half-Life is modeled after a Glock 17, and is replaced by a Beretta 92FS is the graphical overhaul that came with Blue Shift. The weapon isn’t too powerful, although headshots will quickly down enemies. If, however, the player uses the alternative fire method, then the 9mm fires a quick burst of rounds at the expense of range and accuracy.

Magnum Revolver

A revolver that packs quite a punch. While it can only fire single shots, the magnum has a zoom feature that can be accessed by pressing the alternative fire key. Using this zoom feature, the magnum becomes a medium to long range weapon and is far more effective then the 9mm at range. The revolver is modeled after a Colt Python .357 Magnum.

Shotgun

A weapon familiar to all first person shooter fans, the shotgun is easily one of the most powerful close range weapons in the game. Using its alternate fire discharges two shells instead of one, doubling the damage potential but increasing the time between shots. The shotgun is modeled after a Franchi SPAS-12.

SMG

A submachine gun with an attached grenade launcher, a versatile weapon. The MP5 is a rapid fire submachine gun which is great at short to medium ranges. Its alternate fire, a built in grenade launcher, can be devastating, though ammo is limited and the player will be injured by it if too close to the explosion. In the Blue Shift graphical revamp, the MP5 was replaced by an M4 Carbine.

Rocket Launcher

This rocket launcher always hits its mark. The RPG in Half-life isn’t radically different from other shooters, but the special thing about this weapon is that its laser guided. This means wherever the player points the laser the missile will hit, making it a great weapon that’s also quite accurate, at the cost of making it impossible to "fire and forget", requiring the player to expose themselves to enemy fire until the missile hits its target. It does not feature an alternate fire.

Crossbow

Half-Life's crossbow.

The most accurate weapon in the game, the crossbow, in its primary fire mode, fires explosive tipped bolts. The player can greatly increase the range of the crossbow by using its scope

(accessed by pressing the alternative fire key again) and by doing this the crossbow virtually becomes a sniper rifle.

Tau Cannon

The Gauss Gun is an experimental and highly unstable weapon. One of the weapons most important abilities is that it can shoot through walls, meaning no one is safe from its sights. The player can charge the gun up by using the alternative fire key and by doing this the gun will fire a more powerful shot, rather then several weaker shots.

Gluon Gun

Also known as the "Egon", this weapon is a product of Black Mesa’s Weapons Research Facility. The gun fires a constant stream of energy which destroys most things in its path. The weapon's negative point is that shares its ammo with the Gauss Gun, and uses its ammunition very quickly if fired for too long.

Hive-Hand

An alien weapon that basically unleashes swarms of hornets on the enemy. A good medium range weapon but weak in both long and close range. Its ammo regenerates after a few seconds, so it effectively has unlimited ammo.

Snark

A Snark.

These little critters are tossed at the enemy much like a grenade. If there are no enemies nearby, the Snarks will turn on the player, often resulting in a gruesome death. After a period of time the Snarks explode, and while this is a weakness, they are a great weapon partially because they are so much fun.

Fragmentation Grenades

Basic frag grenades are included in Half-Life as well, and tend to be fairly run-of-the-mill. They have a five second fuse and possess no alternate fire, but can be "cooked" by holding down primary fire for a length of time before releasing. Be careful not to hold it for too long.

Satchel Charges

Satchels are essentially remote-activate explosives, which are set by using the primary or alternate fire initially. The player can either choose to detonate the placed satchel, or place additional satchels. Detonating after placing multiple satchels will destory them all at once.

Laser Tripmines

These mines are attached to walls and, after three seconds, project a laser beam that causes the mine to detonate when the beam is broken, either by the player or an enemy. These mines can also destroyed if shot at directly, and are frequently used both online and off to block off paths and restrict player movement.

High-Definition Pack and Weapons

The High-Definition Pack changed several of the weapons in Half-Life, but the changes are mostly aesthetic improvements. However, a few weapons were actually changed into different guns, despite maintaining the same statistics; The MP5 was replaced with an M4 Carbine with an attached M203, the Glock 9mm Pistol was replaced with a Beretta 92F, and modeled the shotgun more closely after a SPAS-12.

Levels

Half-Life doesn't have levels per se, at least not in the normal sense of the word; instead, the player is given an on-screen title whenever a new area loads-- very much like in an interactive book. This apparently simple idea helped the player getting even more immersed in the Half-Live universe and story. Here's a list of those titles:

Anomalous Materials

Unforeseen Consequences

Office Complex

We've got Hostiles

Blast Pit

Power Up

On A Rail

Apprehension

Residue Processing

Questionable Ethics

Surface Tension

Forget About Freeman

Lambda Core

Xen

Gonarch's Lair

Interloper

Nihilanth

End Game

Multiplayer

Half-Life shipped with a multiplayer component that offered standard modes of play, including deathmatch. But its multplayer - and its popularity - got an enormous boost via the release of a free mod known as Counter-Strike. This terrorists vs. counter-terrorists mod was, at one point, one of the most-played online games on the planet. Its popularity carries on to this day.

Ports and Other Versions

Half-Life (PlayStation 2)

Half-Life (PS2).

The PlayStation 2 version is a faithful port of the PC version, but with some changes. Weapons and character models were improved with greater detail and some level geometry was altered.

Most significantly, the game features an expansion called "Decay" which can be played in co-operative mode.

Half-Life: Source

Half-Life: Source

Initially exclusive to the collector edition of Half-Life 2, Half-Life: Source is a direct port of the original single player campaign of Half-Life to Valve's Source Engine.

Half-Life Deathmatch: Source

Half-Life Deathmatch: Source

Much like the prior, Half-Life Deathmatch: Source was initially exclusive to the collector's edition of Half-Life 2 and is a direct port to Valve's Source Engine with no alterations made. As the name suggest, this is a port of the multiplayer component of the original Half-Life.

Black Mesa

Unlike Half-Life: Source, which merely up-rezzed the texture quality of the original game some and used slightly better models, Black Mesa, an entirely fan-made game, actually runs in the Source engine, using cutting edge models and recreating the entire Half-Life experience from scratch. Unfortunately, despite getting the unofficial nod from Valve that would allow them to complete the project without threat of legal action, Black Mesa seems to have been abandoned; the site has not been updated since 2009, and @BlackMesaDevs, the official Twitter account, has not posted since January of 2010.

The first part of Black Mesa Source was finally released on September 14 2012. The game play extends up to the Lambda Core chapter. It is not yet known when the next part will be released.